Tetradonema

Tetradonema	Contents	Rev: 10/09/2024
	Classification	Biology and Ecology
	Morphology and Anatomy	Life Cycle
Return to Tetradonema Menu		Ecosystem Functions and Services
	Distribution	Management
Return to Tetradonematidae Menu	Feeding	References
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Enoplea

Dorylaimia
Mermithida

Mermithina: Tetradonematoidea; Tetradonematidae; Tetradonema Cobb, 1919

Type species of the genus: Tetradonema plicans Cobb, 1919

Synonyms:

Morphology and Anatomy:

Small, naked insect parasites with males smaller than females;
Cuticula without alae (wingless), minutely transversely striated;
Head rounded, tail acute;
Mouth minute, lipless, oral papillae minute, obscure;
Anus absent;
Esophagus simple with tetrad of cells,
Modified intestine extending to tail
Minute stylet in first juvenile stage

Females:

Body sausage shaped, containing hundreds of eggs
Internal anatomy, including esophagus, tetrad of esophageal cells and vagina, obscured by eggs.
Didelphic
Vulva central
Ovaries outstretched
Eggs numerous asymmetrical, throughot body and in capsule-like external structure;
Females of T. plicans > 5 mm long, females of T. solenopsis much samller, around 1.5 mm long.

Body size range for the species of this genus in the database - Click:

Males:

Males minute
Diorchic; testes outstretched
Spiculum single without accessories,
No supplements or bursa

Ref: Ferris and Ferris, 1966; Nickle and Jouvenaz, 1987

Feeding:

Type species is parasitic in larvae of midges (Bradysia coprophila, a mycetophilid fly). Gonad development in parasitized female hosts is reduced.

Tetradonema solenopsis is parasitic on the red imported fire ant, Solenopsis invicta (Nickle and Jouvenaz, 1987). .Adult workers in ant colonies collectd between Cuiaba and Caceres, Mato Grosso, Brazil, were heavily parasitized.

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Biology and Ecology:

All stages of Tetradonema solenopsis occur in adult ants with sausage-shaped female nematodes in the body cavity of each parasitized ant together with a few small males and larvae. In laboratory study, all parasitized ants died in three days.

Living ants parasitized by the nematodeshave slightly enlarged gasters, the dorsal sclerites of which have a scalloped appearance. There were no evident changes in ant behavior (Nickle and Jouvenaz, 1987).

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Life Cycle:

Tetradonema plicans as an example:

Eggs mature eggs female uteri and pass out through the vulva and collect under a layer of cuticle in the midregion of the nematode, forming a capsule. which enlarges until the female may become a huge, quiescent egg sac.
Often the egg capsule swells to fill the interior of the insect host so that the insect becomes a nematode egg sac.
One or more males become attached to the female at mating and remain attached throughout the subsequent development of the female.
Four large cells, which Cobb (1919) called the tetrad, are a prominent feature of mature females and also of males
In many females, the anterior ovary extends nearly to the head and occupies the area filled by the tetrad in the other type of female. Such females became packed with eggs throughout their entire length.
The egg-packed females attain lengths up to 14 mm as compared with an average length of 5 mm for encapsulated females. They also remained very active as contrasted with the quiescent, encapsulated type.
Active femsales escape through a hole in the insect larva or from the posterior end, of the insect larva.
When free, the females todeposit eggs in a water film, 3 or 4 at a time, at intervals of about 30 sec for the first half-hour.
Eggs hatch in water in less than 24 hr, depending on the age of the female from which eggs are taken.
Larvae coiling within the egg appeared to have a very small stylet, as did those which had just hatched but they did not appear to use the stylet for egress from the egg.
Both larvae and adults occur within the hhost insect.

Ref: Ferris and Ferris, 1966

For Ecophysiological Parameters for this genus, click

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Ecosystem Functions and Services:

Regulation of host species.

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Management:

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References:

Cobb, N.A. 1919. Tetradonema plicans nov. gen. et sp., representing a new family, Tetradonematidae as now found parasitic in larvae of the midge-insect Sciara coprophila Lintner. J. Parasitol. 5:176-85.

Ferris, K.M. and Ferris, V.R. 1966. Observations on Tetradonema plicans, an Entomoparasitic Nematode, with a Key to the Genera of the Family Tetradonematidae ( Neniatoda: Trichosyringida ). Annals Ent. Soc. America 59:964-971.

Hungerford, H.B. 1919. Biological notes on Tetradonema plicans Cobb, a nematode parasite of Sciara coprophila Lintner. J. Parasitol. 5:186-192.

Nickle, W.R. and Jouvenaz, D.P. 1987. Tetradonema solenopsis n. sp. (Nematoda: Tetradonematidae) Parasitic on the Red Imported Fire Ant Solenopsis invicta Buren from Brazil. J. Nematology 19:311-313.

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